DIRECTIONS:

» Season steak with 1 teaspoon salt and pepper; set aside. Grate cut sides of tomato on coarse holes of a box grater into a medium bowl down to the skin; discard skin. Add shallot and vinegar; whisk in ¼ cup oil. Season to taste with salt and pepper. Set aside.» Build a medium-hot fire in a charcoal grill, or heat a gas grill to high. Toss spring onions in a medium bowl with 1 teaspoon oil and season with salt and pepper. Grill onions until just tender, 2–3 minutes per side. Transfer to a cutting board and cut into 2-inch pieces. » Grill steak until seared and cooked to desired doneness, 3–5 minutes per side for medium-rare, depending on steak's thickness. Transfer to a cutting board. Let rest, about 10 minutes.» Meanwhile, make croutons: Brush both sides of bread slices with remaining 4 teaspoons oil and season with salt and pepper. Grill bread until dark golden brown and nicely charred in spots, about 2 minutes per side. Set toast aside until cool enough to handle, then break toast into roughly 1-inch pieces.» Thinly slice steak against the grain. Toss lettuces, basil, spring onions, croutons, and some of the vinaigrette in a large bowl. Season to taste with salt and pepper. Add steak and toss gently to coat. Serve with remaining vinaigrette alongside.